Emission properties of Ga2O3 nano-flakes: effect of excitation density

Abstract

In the quest of developing high performance electronic and optical devices and more cost effective fabrication processes of monoclinic β-Ga2O3, new growth techniques and fundamental electronic and optical properties of defects have to be explored. By heating of dissolved metallic Ga in HCl in a NH3 and N2 atmosphere, nano-flake films of monoclinic β-phase Ga2O3 were grown as confirmed by XRD. From optical measurements, we observe two strong emissions. A red band peaking at ~2.0 eV and a UV band at ~3.8 eV. The band at ~2.0 eV is attributed to donor-acceptor pair recombination where the donor and acceptor level is suggested to be related to VO and nitrogen, respectively. By studying the dependence of the intensity of the UV band at 3.8 eV versus excitation density, a model is suggested. In the model, it is assumed that local potential fluctuations forming minima (maxima), where the carriers would be localized with a summarized band offset for conduction and valence band of 1 eV. The origin of the fluctuations is tentatively suggested to be related to micro-inclusions of different phases in the film.

Development of β-Ga2O3 layers growth on sapphire substrates employing modeling of precursors ratio in halide vapor phase epitaxy reactor

“…The feature in our CL spectra at ~ 2.4 eV is close to the green emission at 2.5 eV assigned to excitons bound to intrinsic defects or impurities 22 . We have not observed any dominant red emission at ~ 2.0 eV associated with nitrogen doping 23,24 , since N 2 was used only as a carrier gas during the growth and did not incorporated in the Ga 2 O 3 layers. Recently, Ho et al used a model with an optimized Koopmans-compliant www.nature.com/scientificreports/ hybrid functional allowing to explain different emissions in β-Ga 2 O 3 by the recombination of the bound exciton, where a hole is trapped by intrinsic acceptor levels while electron is weakly localized 25 .…”

High Figure‐of‐Merit Gallium Oxide UV Photodetector on Silicon by Molecular Beam Epitaxy: A Path toward Monolithic Integration

“…Prior literature on the RT photoluminescence (PL) [ 22,23 ] and CL [ 24,25 ] measurements of Ga 2 O 3 epilayers indicates the presence of donor levels in the bandgap due to defects in the form of oxygen vacancy, Ga vacancy, and unintentional doping generated due to the growth limitations. We have observed similar characteristics in RT CL measurements of our Ga 2 O 3 film grown on Si substrates, suggesting that our films follow the nature of their homoepitaxial counterparts.…”

Interface Trap-Induced Temperature Dependent Hysteresis and Mobility in β-Ga2O3 Field-Effect Transistors

“…Beta-gallium oxide (β-Ga 2 O 3 ) is a promising material for power semiconductors due to its superior electrical characteristics, such as a direct wide bandgap (4.6-4.9 eV) [1][2][3][4], a high electric breakdown field (~8 MV/cm) [5][6][7], a high electron saturation velocity (~2×10 7 cm/s) [8], high carrier mobility (~100 cm 2 /V•s) [9][10][11], and thermal/chemical stability [12][13][14]. Furthermore, β-Ga 2 O 3 exhibits the highest Baliga figure of merit (BFoM; defined as εµE G 3 , where ε is the dielectric constant, µ is the mobility, and E G is the bandgap of the semiconductor) [15][16][17] among wide bandgap semiconductors: the BFoM represents a material parameter related to device power dissipation and the value of β-Ga 2 O 3 is approximately ten times and four times higher than those of silicon carbide and gallium nitride, respectively [18,19].…”